I have been trying to solve some throttle problems on my 69 z28. I have cleaned up the throttle shafts and checked for binding everywear. There are no problems, I have used a four hole spacer and an open spacer to clear the vacum fitting.The vacum fitting on my edelbrock performer rpm intake hits the carb without a spacer. Has anyone had any luck with the edlebrock low profule vacum fitting? I am trying to eliminate the spacer as a possibble problem, plus it adds a flat spot and inconsistency to the power band.